The primary end point of our study will be the number of secondary femoral nerve block failure 24 hours past catheter insertion. A dull needle will be used to test the sensory dermatomes for femoral nerve (mid thigh medial aspect). Normal sensation compared with the non-operative site will be considered as failure of the catheter. Secondary catheter failure is defined as the lack of impaired sensory deficit on the medial and anterior aspect of the mid thigh. The study is designed as a pilot study to obtain estimates upon which to base a future larger trial. As such a rigorous sample size calculation is not provided. The goal will be to recruit a minimum of 12 subjects per group, which is the number, required to construct a confidence interval (Statistical Rules of Thumb by Gerald van Belle, 2002, John Wiley and Sons). To account for potential drop out, the number will be increased to 20 per group.